Method for producing dimethyl ether by carrying out gas-phase dehydration on methanol

Abstract

The invention relates to a method for producing dimethyl ether by carrying out gas-phase dehydration on methanol. The method comprises three steps including methanol gas-phase dehydration synthetic reaction, dimethyl ether rectification and methanol rectification. In the methanol gas-phase dehydration reaction, the selectivity is high, the byproduct non-condensable gas is less, and a washing tower is not needed to be separately arranged, so that the upper part of a methanol buffer tank is provided with a washing section for recovering the dimethyl ether, and therefore, the equipment investment is reduced, and the process flow is simple. By taking heat integration into consideration, the number of equipment is reduced as much as possible in the method, so that the equipment investment is reduced, and the process flow is simple and practical. According to the method, a dimethyl ether rectification tower and a methanol rectification tower are plate-type filler combined type towers; tower plates are arranged above the dimethyl ether rectification tower, and dimethyl ether product is adopted by the second tower plate, so that the product is prevented from being polluted by light fraction; and a tower plate is arranged at the middle upper part of the methanol rectification tower, so that fusel oil can be conveniently extracted. The method is easy to operate and control, a heat exchange network is optimized and the heat in the system is effectively utilized, thus achieving the aims of saving energy and reducing emission.

Description

Technical field [0001] The invention belongs to the technical field of dimethyl ether production, and particularly relates to a method for producing dimethyl ether by methanol gas phase dehydration. Background technique [0002] There are one-step and two-step methods for the production of dimethyl ether. The one-step method is to generate synthesis gas from natural gas conversion or coal gasification. The synthesis gas completes the methanol synthesis and methanol dehydration reactions in the reactor at the same time. The two-step method is to synthesize methanol from synthesis gas and then dehydrate to produce dimethyl ether. The two-step method is currently the main process for the production of dimethyl ether at home and abroad. The process is mature and the device has wide applicability. It can be directly built in a methanol production plant. [0003] The domestic dimethyl ether plant tends to be large-scaled. The existing processes have the following problems: the reactor ...

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Problems solved by technology

[0003] The domestic dimethyl ether plant tends to be large-scale development, and the problems existing in the existing process include: the reactor structure is complex, the volume is too large, the temperature control is not sensitive, and it is easy to overheat, etc., which is not conducive to the adoption of large-scale dimethyl ether plant; The liquid phase methanol is recovered by the distillation tower, and then gasified, thus increasing the energy consumption of methanol from gas phase condensation to gasification

The above two methods still have room for optimization in terms of energy saving

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